feat: Add session id in heuristic abuse

[alex-alecu]

Easily find what session has possibility of abuse /admin/users/..../heuristic-abuse

[kiloconnect]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

This PR adds a session_id field (sourced from the X-KiloCode-TaskId header) to the usage tracking pipeline. The implementation is thorough and consistent:

• Schema & Migration: session_id column added to microdollar_usage_metadata table and microdollar_usage_view with a proper Drizzle migration.
• Type safety: session_id added to both MicrodollarUsageContext and UsageMetaData types, flowing correctly through extractUsageContextInfo.
• Input sanitization: Uses extractHeaderAndLimitLength (truncates to 500 chars) — consistent with how machine_id and editor_name are handled.
• SQL insert alignment: Column and value positions match correctly in the raw SQL insert.
• All callsites updated: openrouter route, FIM route, consume-credits dev route, admin insert-usage-record route, and test helpers all include session_id.
• Tests: New test case verifies session_id storage, existing test updated to assert null default.

Files Reviewed (11 files)

• src/db/schema.ts
• src/db/migrations/0021_orange_maggott.sql
• src/db/migrations/meta/0021_snapshot.json
• src/db/migrations/meta/_journal.json
• src/lib/processUsage.ts
• src/lib/processUsage.test.ts
• src/app/api/openrouter/[...path]/route.ts
• src/app/api/fim/completions/route.ts
• src/app/api/dev/consume-credits/route.ts
• src/app/admin/api/users/[id]/dev/insert-usage-record/route.ts
• src/app/admin/components/UserAdmin/UserAdminHeuristicAbuse.tsx
• src/scripts/usage/benchmark-insert-usage.ts
• src/tests/helpers/microdollar-usage.helper.ts